chore(deps-dev): bump @storybook/theming from 6.2.0-rc.2 to 6.2.0-rc.4

Bumps [@storybook/theming](https://github.com/storybookjs/storybook/tree/HEAD/lib/theming) from 6.2.0-rc.2 to 6.2.0-rc.4.
- [Release notes](https://github.com/storybookjs/storybook/releases)
- [Changelog](https://github.com/storybookjs/storybook/blob/next/CHANGELOG.md)
- [Commits](https://github.com/storybookjs/storybook/commits/v6.2.0-rc.4/lib/theming)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -81,7 +81,7 @@
     "@storybook/core": "6.2.0-rc.4",
     "@storybook/html": "6.2.0-rc.4",
     "@storybook/source-loader": "6.2.0-rc.4",
-    "@storybook/theming": "6.2.0-rc.2",
+    "@storybook/theming": "6.2.0-rc.4",
     "@wojtekmaj/enzyme-adapter-react-17": "^0.4.1",
     "angular": "^1.8.2",
     "angular-mocks": "^1.8.2",